Explanation:
Also known as the Cigar Galaxy for its elongated visual appearance,
M82 is a starburst
galaxy with a superwind.
In fact,
through ensuing supernova explosions and
powerful winds from massive stars,
the burst of star formation in M82
is driving a prodigious outflow.
Evidence
for the superwind from the galaxy's central regions
is clear in
this
sharp telescopic snapshot.
The composite image highlights emission from
long outflow filaments of atomic hydrogen gas in reddish hues.
Some of the gas in the superwind,
enriched in heavy elements
forged in the massive stars,
will eventually escape into
intergalactic space.
Including narrow band image data in the deep exposure
has revealed a faint
feature dubbed the cap.
Perched about 35,000 light-years above the galaxy at the upper left,
the cap appears to be galactic halo material.
The material has been ionized by the superwind shock
or intense ultraviolet radiation from the young, massive stars
in the galaxy's core.
Triggered by a close encounter with
nearby large galaxy M81,
the furious burst of star formation in M82 should last about
100 million years or so.
M82 is 12 million light-years distant, near the northern boundary of
Ursa Major.